What type of 2TB SSD does Apple use with the 2019 iMac 27

According the the MacTracker database, there are two drive buses:

1 - 6.0 Gbps Serial ATA (SATA), 1 - 8.0 GT/s NVMe PCIe x4

A factory SSD would be on the NVMe PCIe bus. That is where the 1TB Apple SSD in my 2017 iMac 5K resides.

Thanks! Fun stuff indeed.

The crazy thing is what the bottle-necked drive in our 2011 entry-level iMac reports--those scores above are higher than many new models! The only hardware upgrade is I added 4GB RAM several years ago so it is now at 8GB.

Current 21.5 iMacs have the same lame-brain setup: a 3GBps 5400rpm SATA drive connected to a 6GBps drive bus. Why this has persisted so long I do not know. This is the SysInfo SATA bus report from my daughter's 2017 21.5 4K:

We are seeing the same metric from current iMacs that post R/W speeds less than half than what I get on our old web warrior from 2011. Some of it comes down to unneeded software clutter; ours is about as clean as it can be. However, I've seen people clean all the dreckware off their newer iMAcs and still not hit the 90 MBps mark.

You are most welcome. I saved $100 by getting the extra RAM from OWC and put that towards the SSD. I don't trust the Fusion drives.

EtreCheck runs a drive performance check and these are the read/write speeds my 2017 iMac posted with the 1TB Apple drvie:

Performance:

    System Load: 1.66 (1 min ago) 1.42 (5 min ago) 1.31 (15 min ago)

    Nominal I/O speed: 0.23 MB/s

    File system: 20.35 seconds

    Write speed:  2156 MB/s

    Read speed:  2863 MB/s

For comparison this is my 2102 MBP with an inexpensive aftermarket 6GBps SSD on the SATA bus (also 6GBps):

Performance:

    System Load: 1.61 (1 min ago) 1.60 (5 min ago) 2.94 (15 min ago)

    Nominal I/O speed: 0.15 MB/s

    File system: 28.20 seconds

    Write speed: 487 MB/s

    Read speed: 482 MB/s

and, for a stroll down Memory Lane, this is the factory 3GBps 5400rpm drive (connected to a 6GBps SATA bus) in the wife's 2011 iMac:

Performance:

    System Load: 1.62 (1 min ago) 1.67 (5 min ago) 1.87 (15 min ago)

    Nominal I/O speed: 0.05 MB/s

    File system: 38.28 seconds

    Write speed:  112 MB/s

    Read speed:  91 MB/s